The rapid proliferation of optical fiber telecommunications systems has made possible the provision of broadband services to individual subscribers on a relatively universal basis. Such broadband services often include data transmission; however, there is a broader market for the distribution of video signals over the telecommunications network.
The provision of such video services has long been desired; however, the previously proposed systems have all been subject to various deficiencies which have prevented their commercial acceptance. Video signals may be broadcast to all subscribers over optical fibers; however, this severely limits the programming selection and the number of channels that may be available to each subscriber. A switched video architecture allows for the provision of significantly more programming options and control of distribution only to authorized subscribers.
The concept of switched video transmission systems has been proposed in the past; however, most proposals have had undesirable features. Most proposed switched video architectures require the use of a second optical fiber to distribute the broadband services. The use of two fiber systems to distribute the broadband video service is inefficient in that the second fiber must be installed during the initial deployment of the system when there are extremely high equipment expenses. Currently, regulatory agencies do not always permit recovery of costs associated with a second fiber for broadband services.
Other systems have used a separate narrowband telephone connection for keying in control data in the upstream direction using a telephone subset. Such systems are not truly integrated and require the use of the premises telephone subset to transmit control information upstream for selection of the desired video. The RCV-1G system (i.e. Reseau Communication Video 1G) provided by Alcatel used a dedicated FSK subcarrier electrically multiplexed with the narrowband and video for control purposes. Thus, the prior art has not provided a commercially acceptable architecture for mass deployment of switched video on a telecommunications network.
In still other known systems, there is an undesirable need to use expensive tuners or converters on each set to selectively distribute both scrambled and descrambled channels. This problem is further aggravated by subscribers who use unauthorized converters to descramble channels to avoid paying service charges, which results in large economic loss to the provider of the service.